1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Help new MAF still poor economy

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by streaker, Nov 10, 2012.

  1. streaker

    streaker Active Member

    Messages:
    42
    Likes Received:
    0
    Joined:
    Nov 4, 2012
    Location:
    Somerset
    Your Mercedes:
    C220 Estate 2004 2.2 Diesel
    Hi all

    I posted last week about my sudden drop in MPG down to 28mpg from 45mpg, after changing the filters and thermostat with no improvement, I disconnected the MAF and this gave an instant improvement, over the week i did 450miles and returned 50mpg with 400miles on the motorway @ around 80mph,

    So today I fitted a brand new Bosch MAF and am disappointed to find I'm only getting around 35 mpg although the engine feels more refined,

    When I bought the car I was told that the dpf had been deleted from the ECU and the dpf internal's removed along with a remap for more power, the car certainly has a lot of torque but belts out a lot of black smoke on kick down
    the smoke disappeared with the MAF disconnected but has come back with the new MAF

    any idea's to my problem will be much appreciated

    PS can anyone recommend an indy in the liverpool area ?

    Jaz
     
  2. oigle

    oigle Senior Member

    Messages:
    2,894
    Likes Received:
    182
    Joined:
    Mar 15, 2005
    Location:
    Redcliffe, Queensland, Australia
    Your Mercedes:
    Currently 2003 ML270. 2012 Nissan Maxima 250SL.
    When the ecu signals the EGR to open, it also signals the maf to alter its parameters to compensate for flow through the egr. By disconnecting the maf, you would have prevented that happening. This would cause unusual fueling.
    Perhaps, the EGR is part of the problem - a sticking egr is well known as a cause of very excessive black smoke on acceleration. A check of its operation and a good clean might help. Of course, an egr delete would be the best option.
     
  3. OP
    streaker

    streaker Active Member

    Messages:
    42
    Likes Received:
    0
    Joined:
    Nov 4, 2012
    Location:
    Somerset
    Your Mercedes:
    C220 Estate 2004 2.2 Diesel
    Hi Oigle

    yes i 'd love to get rid of the pesky egr ( I was unfortunate enough to buy a renault lagunaII tdi, the egr on that car caused thousands of £'s worth of problems)

    Is it possible to easily delete on my car ? its a face lift model with electronic egr control

    although the smoke is a pain its the economy thats my priority

    disconnecting the Maf saved £20.00 for 180 mile journey

    cheers

    Jaz
     
  4. oigle

    oigle Senior Member

    Messages:
    2,894
    Likes Received:
    182
    Joined:
    Mar 15, 2005
    Location:
    Redcliffe, Queensland, Australia
    Your Mercedes:
    Currently 2003 ML270. 2012 Nissan Maxima 250SL.
    Someone like Alex Crow can comment re whether you can delete the EGR on your motor. I don't know the various models well enough. There is one system that, as yet, can't be removed. You might be lucky.
    The comments I made earlier were directed at the economy and whether the EGR/MAF relationship could have had any bearing on it. After all, black smoke is wasted fuel.
     
  5. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

    Messages:
    6,808
    Likes Received:
    961
    Joined:
    Dec 8, 2009
    Location:
    Bristol/Somerset
    Your Mercedes:
    C220CDI AMG Line Premium, SLR McLaren Roadster, SL55 & C32AMG
    The issues on smoking on throttle is not caused by the EGR but a build up of soot in the inlet manifold. Done a couple for this now, usually the EGRs are operational, doing there job and although a bit sooty, what you would expect to see. The soot collects in the chambers of the inlet manifold and once removed and cleaned they dont smoke at all. I did one for a forum member here and he is reporting a 5mpg increase and a lot more power too!

    I had a car in a few weeks ago that had an DPF delete and a remap, it also had poor economy as well as intermitantly dropping into limp mode. I found that although the DPF had been deleted it still had a value for the differential pressure sensor, these sensors were modified in 05 and this one had an old style one fitted. I replaced the sensor and all was well.

    Its all very well deleting this and that but it can cause so many issues when it comes to running problems as you can never be sure what values are what and what really is causing running problems. The one I had you would think it would ignore the pressure sensor as the DPF was removed, but the engine management will not run the engine properly without seeing a value from that sensor.

    I am a great believer in actually fixing things instead of cutting things out to short cut other issues. It is a case of short term gain but long term pain.
     

Share This Page